The present invention relates to a resistance film tablet system and a method of controlling the resistance film tablet system, and particularly to a resistance film tablet system comprising two resistance films superposed on each other and spaced by a predetermined distance therebetween and a method of controlling the resistance film tablet system.
Conventionally, a resistance film tablet system is composed of two resistance films which have resistance values equal to each other and each of which has parallel electrodes at both ends thereof. The two resistance films are then faced to each other to have a space of a predetermined distance therebetween with their directions shifted by 90 degrees from each other. With this structure, when the two resistance films are pressed from outside by a tapered tip like a pen tip and so on, the two resistance films are arranged to come into contact with each other at the pressed point.
Regarding the four parallel electrodes of such a tablet, it is known that a physical position of the contact point of the two resistance films can be measured by using the following scanning modes.
As will later be described more in detail, the conventional resistance film tablet system is subjected to the following basic scanning modes. Namely, the modes consist of "contact detection" to check whether or not the two resistance films are in contact with each other, "X-detection" to check a position in the direction of X, and "Y-detection" to check a position in the direction of Y. And, these detecting modes or operations are sequentially repeated until the two resistance films are judged as being not in contact with each other in the "contact detection" mode.
In addition, it is a recent trend that a faster sampling is required from demands for a character recognition with a normal writing speed, etc.
However, when users measure contact point voltages by the X-detection and the Y-detection modes in the conventional resistance film tablet system, they have to wait a certain period of time due to a change of a mode. Thereby, sampling is substantially restricted. In other words, when contact point voltages are measured by the X-detection and the Y-detection, tablet scanning of the conventional resistance film tablet system has a drawback that users have to wait a certain period of time after a mode is set.